Abstract：
Acoustics recordings from laser-induced plasmas are becoming increasingly regarded as a complementary source of information from the inspected sample. The propagation of these waves is susceptible to be modified by the physicochemical traits of the sample, thus yielding specific details that can be used for sorting and identification of targets. Still, the relative fragility of the acoustic wave poses major challenges to the applicability of laser-induced acoustics. Echoes and reflections sourcing from intrasample parameters as well as from interactions of the acoustic wave with the surroundings of the inspected target can dilute the analytical information directly related to the object contained within the recordings. The present work aims to experimentally scrutinize the impact of different parameters internal and external to the sample into the final acoustic signal from laser-induced plasmas in order to accurately use this information source for characterization purposes. Variables inherent to the sample such as dimensions, porosity and absorption coefficient, which guides the laser-matter coupling process, have been, for the first time, systematically studied using ad-hoc solids to thoroughly isolate their influence on the signal. Moreover, modulation of soundwave induced by the surroundings of the probed target and the anisotropy of the acoustic signal because of the angle at which the plasma is formed, have been evaluated.
摘要：
来自激光诱导等离子体的声学记录越来越被视为来自被检查样品的信息的补充来源。这些波的传播很容易被样品的物理化学特性所改变，从而产生可用于目标的分类和识别的具体细节。尽管如此，声波的相对脆弱性对激光诱导声学的适用性提出了重大挑战。来自样本内参数以及来自声波与被检查目标的周围环境的相互作用的回波和反射可以稀释与记录内包含的对象直接相关的分析信息。本工作旨在通过实验检查样品内部和外部不同参数对激光诱导等离子体最终声信号的影响，以便准确地使用此信息源进行表征。样本固有的变量，如尺寸，孔隙率和吸收系数，引导激光-物质耦合过程，一直以来,第一次,使用ad-hoc固体进行系统研究，以彻底隔离它们对信号的影响。此外，由于形成等离子体的角度，由探测目标的周围环境引起的声波调制和声信号的各向异性，已被评估。
